Question

1. Use a For loop to compute the sum of all the odd numbers from 1 through 99. Your result should be labeled, and the value should be 2500.
   
2. Print your name 7 times using a While loop.
   
3. String dogNames[ ] = {"Sam","Buster","Fido","Patches","Gromit","Flicka"};
   Using the array defined here, print the values of the array vertically and horizontally using one For-Each loop.
   
4. Reverse the logic for zyBook Challenge activity 4.6.1 (Nested loops: Indent text) so that the first line is indented userNum number of spaces and the subsequent lines are each indented one less space until the last value is not indented at all (‘s’ indicates one space):
   sssss5
   ssss4
   sss3
   ss2
   s1
   0
   
5. String method practice:
   • Create a String variable that contains your full name
   • Repeat the following steps 5 times (note you will use predefined String methods to modify your name as indicated):
     • Generate a random number between 1 and 4
     • If number is 1, display your name in all upper case
     • If number is 2, display your name in all lower case
     • If number is 3, replace your first name with “Three” and display your name
     • If number is 4, display the character at index 4

Answer 1

SumOfOdd.java

class SumOfOdd
{
   public static void main(String args[])
   {
       //sum variable which store the sum of odd numbers
       int sum=0;
       //iterate for loop from 1 to 99 inclusively
       for(int i=1;i<=99;i++)
       {
           //If i is odd then add i to sum
           if(i%2==1)
           {
               sum=sum+i;
           }
       }
       //print the reuslt
       System.out.println("Sum of odd numbers between 1 to 99 is: "+sum);
   }
}

output screenshot:

NamePrint.java

class NamePrint
{
   public static void main(String[] args)
   {
       //n denotes number of times to print
       int n=7;
       //name initialization
       String name="ABC DEF GHI";
       //Iterate while loop for 7 times
       while(n>0)
       {
           //Print the result
           System.out.println(name);
           //decrement n by 1
           n--;
       }
   }
}

output screenshot:

ArrayPrint.java

class ArrayPrint
{
   public static void main(String[] args)
   {
       //array of names initialization
       String dogNames[ ] = {"Sam","Buster","Fido","Patches","Gromit","Flicka"};
       //Iterate over array of names
       for(int i=0;i<dogNames.length;i++)
       {
           //print horizontal manner
           System.out.print(dogNames[i]+" ");
       }
       //New line for printing result in vertical manner
       System.out.println();
       //Iterate over array of names
       for(int i=0;i<dogNames.length;i++)
       {
           //Print vertical manner
           System.out.println(dogNames[i]);
       }      
   }  
}

output screenshot:

IndentText.java

class IndentText
{
   public static void main(String[] args)
   {
       //initialization of userNum
       int userNum=5;
       //iterate userNum times
       for(int i=userNum;i>=0;i--)
       {
           //iterate from 1 to i inclusive
           for(int j=1;j<=i;j++)
           {
               //print s denotes the space
               System.out.print("s");
           }
           //print i
           System.out.println(i);
       }  
   }
}

output screenshot:

StringOperation.java

//importing Random class
import java.util.Random;
class StringOperation
{
   public static void main(String[] args)
   {
       //Initialization of fullName
       String fullName="ABCDEFG HIJK";
       //creating object for Random class
       Random rand = new Random();
       //n denotes the number of time that while loop repeats
       int n=5;
       while(n>0)
       {
           //generate random numebr between 1 to 4
           int i=rand.nextInt(4)+1;
           //If i is 1 then print full name in upper case
           if(i==1)
           {
               System.out.println(fullName.toUpperCase());
           }
           //If i is 2 then print full name in lower case
           else if(i==2)
           {
               System.out.println(fullName.toLowerCase());
           }
           //if i is 3 then replace first name with Three
           else if(i==3)
           {
               //find the index of first space
               int index=fullName.indexOf(' ');
               //repalce first name with Three
               fullName="Three "+fullName.substring(index+1);
               System.out.println(fullName);
           }
           //If i is 4 print the character at 4th index
           else if(i==4)
           {
               System.out.println(fullName.charAt(4));
           }
           //decrement n by 1
           n--;
       }
   }
}

output screenshot: